Rock drill joint



Feb. 1, 1938. DES oc s 2,107,238

ROCK DRILL JOINT Filed July 12, 1937 Patented Feb. 1, 1938 UNITED STATS ATENT ()FFECE 6 Claims.

This invention relates to rock drills and particularly to a form of joint or connection for detachably securing the bit to the shank of the drill. The object of the invention is to provide a joint or connection by which the bit is firmly and tightly secured to the shank, but which also permits ready detachment of the bit to allow replacement or sharpening of the same. A further object is to obviate the use of pins or springs for holding the bit on the shank, as such arrangements are open to considerable objection. The advantages of the invention will further appear from the following specification in connection with the accompanying drawing, in which Figure l is a side view of a combined bit and shank involving the invention with the parts in operative position;

Figure 2 is a view similar to Figure 1 with the bit slightly separated from the shank;

Figure 3 is also a side view of the combined bit and shank taken at right angles to Figure 1;

Figure 4 is an enlarged perspective view of the end of the shank;

Figure 5 is an enlarged perspective view of the end of the bit which engages the end of the shank; and

Figure 6 is an enlarged cross-section showing the relation of certain parts on the shank and bit.

As shown in the drawing, the bit II] is preferably made generally rectangular in cross-section, and the working surface thereof is provided with pyramidal projections as in my prior Patent No. 1,561,975, although the present invention is not limited to such features. The bit 10 is provided on one end, conveniently referred to herein as the upper end, with an upwardly projecting looking tongue l2 which extends the full width of the bit as shown in the drawing. At its upper end the tongue l2 isv provided with an enlarged generally cylindrical portion or head l3, and the tongue itself is made slightly Wedge-shaped, being somewhat thicker at the point l4 adjacent the body of the bit than it is adjacent the head l3.

The shank I5 is provided at its end adjacent the bit, conveniently referred to as the lower end, with a slot or recess it which is adapted to receive the tongue I2 of the bit. This recess comprises an enlarged portion ll and a somewhat narrow or constricted throat i8 which is adapted to tightly fit and receive the thicker portion is of the wedge-shaped tongue l2 on the bit. The enlarged head l3 on the tongue I2 is somewhat larger than the throat 18 so that the bit l0 and (01. 255-63) l v shank l5 cannot be completely separated'by movement in a direction parallel to the axis of the shank. However, limited movement or separation of the bit and shank is permitted, as shown in Figure 2, by the fact that the portion I! of the recess It in the shank is somewhat larger than the head It on the tongue 52. When the bit is thus partly separated from the shank, itcan be moved laterally relative to the shank, and the two parts may thus be separated from each other.

The upper surfaces on the bit and the lower co -operating surfaces on the shank are preferably made so as to prevent lateral movement between the bit and shank when said surfaces are in contact. To this end the shank is provided with lower surfaces 20 on each side of the slot l6. Each surface 20 inclines upwardly toa slight extent from the outer edge thereof toward said slot. each end toward the center of the shank indicatedat C. On each side of the slot IS a flat surface2| is also preferably formed.

The bit ill is provided with surfaces which are complementary to and which are adapted to fit against the above described surfaces on the shank when the two, parts are assembled. Thus, on each side of the tongue [2 the bit is formed with inclined surfaces 22 and flat surfaces 23 which are complementary respectively to and fit against the surfaces 2!] and 2| on the shank. The result is that when the bit If! is forced tightly against the shank, the complementary surfaces 20 and 22 closely engage each other and prevent any lateral movement of the bit relative to the shank in any direction.

In assembling the parts the bit is moved laterally of the shank with the enlarged head l3 of the tongue engaging the enlarged portion H of the recess Hi. When the surfaces 28 and 22 are in alignment, the tongue 12 is then forced into the recess it until the tongue wedges tightly in the narrow throat ll! of the recess or slot, and at the same time the cooperating surfaces 20, 22 on the shank and bit are brought into engagement and serve to accurately center the bit on the shank and prevent any lateral movement of one part relative to the other.

In operation the small space 24 in the slot l6 above the head I3 is soon filled and tightly packed with chips or cuttings which further serve to hold the bit in place on the shank. To disconnect the parts, it is a simple matter to remove Also each surface inclines upwardly from slight blow on the bit loosens its wedged engagement with the shank, after which the bit can be separated slightly from the shank and then moved laterally to disengage the tongue thereof from the slot in the shank.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is: V V

1. In a rock drill, a shank having a slot extending transversely across the end thereof, a bit having a tongue adapted to enter said slot by lateral movement of the bit relative to the shank, means to prevent separation of the bit from the shank by movement of the bit axially of the shank, said slot having a constricted throat and said tongue having a wedge shaped portion adapted to tightly wedge in said slot when the bit is forced axially toward the shank, and cooperating means on the shank and bit to prevent lateral movement of the bit relative to the shank when said tongue is forced into said throat.

2. In a rock drill, a shank having a slot extend' when the bit is forced axially of the shank and said tongue is wedged in said throat. V

3. In a rock drill, means for detachably securing a bit to a shank, comprising a slot in one of said parts and a tongue on the other part adapted to enter said slot when one part is moved laterally relative to the other part, said slot having a constricted throat and said tongue having a wedgeshaped portion adapted to tightly engage in said throat when the bit and shank are forced axially toward each other, said bit and shank having cooperating parts arranged to engage and prevent lateral movement of the bit relative. to the shank When said tongue is forced into said throat.

i, In a rock drill, means for detachably securing a bit to a shank, comprising a slot in one of said parts and a tongue on the other part adapted to enter said slot when one part is moved laterally relative to the other part, said slot having a constricted throat and said tongue having a wedgeshaped portion adapted to tightly engage in said throat when the bit and shank are forced axially toward each other, said bit and shank having cooperating complementary surfaces thereon inclined relative to the axis of the shank and arranged to engage when said tongue is forced into said throat, whereby lateral movement of the bit relative to the shank is prevented.

5. In a rock drill, a shank having a slot extending across the end thereof, said slot having a constricted throat and an enlarged portion back of said throat, a bit having a tongue on one end thereof, said tongue having an enlargement on the outer part thereof, said tongue being constructed to enter said slot by lateral movement of the bit relative to the shank, said enlargement on the tongue being of such size as to prevent withdrawal of said tongue from said slot in a direction axially of the shank, said tongue also having a wedge-shaped portion thereon which is adapted to tightly wedge in said throat when said bit is forced axially toward said shank, said bit and said shank having cooperating surfaces thereon arranged to engage and prevent lateral movement of the bit relative to the shank when said tongue is forced into said throat.

6. In a rock drill, a bit and a shank, one of said parts having a slot provided with a constricted portion and the other having a tongue constructed to wedge in said constricted portion of the slot by axial movement of the bit relative to the shank, and cooperating surfaces on the bit and shank arranged to engage and prevent lateral movement of the bit relative to the shank ina direction parallel to said tongue or slot when said tongue is forced into the constricted portion of said slot, said tongue having an enlargement thereon to prevent withdrawal of the tongue from the slot in a direction parallel to the axis of the shank.

HILTON H. DES ROCHES. 

